Data recording and reproduction systems for recording, for example, video, audio or computer data on a disc-like recording medium and reproducing such data from a recording medium are widely used. Specifically, optical discs such as CDs (compact discs), DVDs (digital versatile discs), BDs (Blu-ray discs) and the like, and optical disc apparatuses compatible therewith; opto-magnetic discs such as MOs (magnetic optical discs), MDs (minidiscs) and the like, and opto-magnetic disc apparatuses compatible therewith; and magnetic discs such as FDs (floppy discs) and magnetic disc apparatuses compatible therewith are already in wide use in the society.
Because of the rapid increase of data amount of such information in recent years, a recording medium having a large capacity is desired. Among the above-mentioned recording and reproduction systems, those using optical discs or opto-magnetic discs use record data in the form of minute recording marks using a light beam, and reproduce data from reflected light obtained by irradiating recording marks with a light beam. Hereinafter, the optical discs and the opto-magnetic discs will be collectively referred to as “optical discs”, and the optical disc apparatuses and the opto-magnetic disc apparatuses will be collectively referred to as “optical disc apparatuses”.
In order to record data at a higher density using an optical disc, it is necessary to form a smaller recording mark. For this purpose, an optical disc apparatus needs to provide highly precise control on an optical pickup for irradiating an optical disc with a light beam to perform recording or reproduction, so that smaller recording marks can be accurately formed and data can be accurately read from the recording marks thus formed.
Such optical disc apparatuses are incorporated into a wide range mobile devices. A mobile device is carried around, or held or used at a position high from the ground or floor by a user. Hence, the user may inadvertently drop the mobile device. When this happens, an optical pickup, which is a moving mechanism in the optical disc apparatus, receives an impact force due to the dropping. A conventional optical disc apparatus for mobile devices has a structure for inhibiting malfunctioning which could otherwise occur due to such an impact force. Hereinafter, an example of such a conventional optical disc apparatus will be described. This structure is disclosed in, for example, Patent Document 1.
A conventional optical disc shown in FIG. 40 includes a turntable 101 for allowing a spindle motor 103 and a disc to be mounted thereon. The turntable 101 is rotated and driven by the spindle motor 103. FIG. 40 does not show the disc or any chucking member for securing the disc.
The optical disc apparatus further includes an optical pickup 105 for emitting a light beam to perform recording to, or reproduction from, the disc. The optical pickup 105 is guided by a main guide shaft 107A and a sub guide shaft 107B in a radial direction of the disc placed on the turntable 101. The main guide shaft 107A and the sub guide shaft 107B are supported by bearings 109A, 109B, 109C and 109D.
A transportation motor 111 is a driving source for transporting the optical pickup 105 in the radial direction of the disc placed on the turntable 101. A driving force obtained by the transportation motor 111 is transmitted to the optical pickup 105 by a lead screw 113 rotatable via a continuous spiral groove formed on a circumferential surface thereof and by a transmission member 115 engaged with the lead screw 113 to transmit a thrust for transporting the optical pickup 105 in the radial direction of the disc. A base member 117 supports these elements integrally.
In the structure shown in FIG. 40, the transportation motor 111 is driven to transport the optical pickup 105 in a direction of arrow D101A or arrow D101B, which is the radial direction of the disc. Thus, the optical pickup 105 performs a recording operation or a reproduction operation at an arbitrary radial position of the disc.
FIG. 41 shows a state in which the transmission member 115 and the lead screw 113 are engaged with each other. The transmission member 115 includes an engaging section 115A having teeth 115AB and 115AC engageable with a spiral groove 113A of the lead screw 113, and a regulating part 115B for preventing the teeth 115AB and 115AC from coming off from the spiral groove 113A.
Owing to the regulating part 115B, when the optical pickup 105 receives an excessive transportation force by an impact or the like in a transportation direction, the engaging section 115A is prevented from moving in a direction perpendicular to the transportation direction, and so the teeth 115AB and 115AC are prevented from coming off from the spiral groove 113A. Thus, such a situation that the transmission member 115 is disengaged from the lead screw 113 and the optical pickup 105 cannot be not driven is avoided.                Patent Document 1: Japanese Laid-Open Patent Publication No. 2002-339882        